Flexible abrasive product and method of making and using the same

ABSTRACT

The present invention provides a flexible abrasive product comprised of an open cell foam backing, a foraminous barrier coating and a shaped foraminous abrasive coating. The flexible abrasive article of the invention is made by applying a curable barrier coating over an open cell foam backing, curing the curable barrier coating to provide a foraminous barrier coating having openings therethrough corresponding to openings in the open cell foam, applying a coating composition comprising a curable binder and abrasive particles over the foraminous barrier coating, imparting a textured surface to the coating composition with a production tool which has a textured surface which is the inverse of the textured surface of the abrasive coating and to which production tool textured surface any coating composition coated over an opening of the first major surface may adhere, at least partially curing the binder, and separating the production tool from the textured surface to provide the shaped foraminous abrasive coating.

RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.09/706,033, filed Nov. 3, 2000 and U.S. patent application Ser. No.09/850,661, filed May 7, 2001, incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to flexible abrasive articles,such as abrasive sponges. More particularly, the present inventionrelates to a flexible abrasive product comprised of a foam backing and ashaped abrasive coating.

BACKGROUND OF THE INVENTION

The use of abrasive products to finish the painted surface of a repairedportion of an automobile is well known. The original painted exteriorsurfaces of automobiles have a unique “orange peel” surface that isdesirably duplicated when repairs are made. While prior coated abrasiveproducts and abrasive slurries, either alone or in combination,typically in the presence of a liquid medium such as water, have beenused to finish such surfaces, finishing techniques that use theseproducts have produced less than optimal results.

Various patents disclose products and/or processes which are said to beuseful for finishing painted automotive surfaces. See for example, EP 0771 613 B1, published Apr. 5, 2000, WO 00/03840, published 27 Jan., 2000based on U.S. patent application Ser. No. 09/116,038 filed Jul. 15,1998, and U.S. Pat. No. 6,024,634.

Several problems are encountered by use of finishing products and/ortechniques that are known in the art. These include the inability toprovide a finished orange peel surface that duplicates the originalsurface. Additionally, some products encounter unwanted sticking to orgrabbing between the moistened painted surface being finished and thesurface of the abrasive product as it is rotated, for example on a “dualaction” sander, or otherwise moved against the surface being finished.Other products are difficult to use. Some are thin with apressure-sensitive adhesive attachment system and are difficult toremove from a release liner and, when attached to a support pad, are noteasily deployed wrinkle-free.

A need exists for a flexible abrasive product which will refine apainted exterior automotive surface to provide a surface finish which,after a subsequent glazing step, substantially duplicates the originalpainted surface substantially without disturbing the orange peel. A needalso exists for a flexible abrasive product which, when used under wetconditions with a dual action sander, will not grab the surface beingfinished.

SUMMARY OF THE INVENTION

This invention provides a flexible abrasive product, a method of makingthe same and a method of using the same. The novel abrasive product,when used under wet conditions to refine a painted exterior automotivesurface which, after a subsequent glazing step, provides a surfacefinish which substantially duplicates the original painted surfacewithout substantially disturbing the orange peel. In use with a dualaction sander under conventional wet conditions, the novel flexibleabrasive product will not grab or stick to the surface being finished.

In one embodiment, the invention provides a flexible abrasive articlecomprising:

-   -   a. foam backing having a minimum thickness of at least 2 mm, a        first major surface and an opposite second major surface; and    -   b. a shaped abrasive coating over said first major surface of        the foam backing comprised of abrasive particles in a binder.        The foam backing in this embodiment may be a closed cell foam or        an open cell foam.

In a further embodiment, the invention provides a flexible abrasivearticle which comprises:

-   -   a. an open cell foam backing having a first major surface and an        opposite second major surface;    -   b. a foraminous barrier coating over said first major surface;        and    -   c. a shaped foraminous abrasive coating over the foraminous        barrier coating comprised of abrasive particles in a binder.

The open cell foam preferable is in sheet form with planar majorsurfaces, but other surface-configurations are also useful. For example,the second major surface may be planar to facilitate attachment and thefirst major surface, i.e., the surface to which the abrasive coatingwill be applied, may be other than planar, such as an undulated orconvoluted surface. Such convoluted foams are disclosed in U.S. Pat. No.5,007,128, incorporated herein by reference.

While the flexible abrasive product according to the invention may beused by hand without an attachment system, it typically includes anattachment system on the second surface for attaching the abrasivearticle to a support pad. Such attachment system may include, forexample, one part of a hook and loop fastening system with the otherpart of the hook or loop being on the support pad of the sander orabrasive tool which will be utilized to move the flexible abrasiveproduct. Other types of fastening systems may include a coating ofpressure-sensitive adhesive of a pressure-sensitive adhesive compositionwhich is attachable to a smooth surface on the support pad of the tool.

In one embodiment the flexible abrasive article is made by a methodwhich comprises the following steps:

-   -   a. providing a foam backing having a minimum thickness of at        least 2 mm, a first major surface, and an opposite second major        surface;    -   b. adhering to the second major surface one part of a two part        attachment sheet material to provide dimensional stability to        foam backing;    -   c. applying a shaped coating composition comprising a curable        binder and abrasive particles over said first major surface of        foam backing, said coating composition being curable to provide        a shaped abrasive coating; and    -   d. curing the curable binder.

The flexible abrasive article of the invention in a further embodiment,is made by a method which comprises the following steps:

-   -   a. applying a curable barrier coating over a first major surface        of an open cell foam backing which also has an opposite second        major surface;    -   b. curing the curable barrier coating to provide on the first        major surface a foraminous barrier coating having openings        therethrough corresponding to openings in the open cell foam;    -   c. applying a coating composition comprising a curable binder        and abrasive particles over the foraminous barrier coating;    -   d. imparting a textured surface to the coating composition        applied in step c with a production tool that has a textured        surface which is the inverse of the textured surface of the        abrasive coating and to which production tool textured surface        any coating composition coated over an opening in the first        major surface may adhere;    -   e. at least partially curing the binder; and    -   f. separating the production tool from the textured surface to        provide the shaped foraminous abrasive coating characterized by        having openings therethrough corresponding to at least some of        the openings in the open cell foam.

Alternatively, the flexible abrasive product may be made by thefollowing method:

-   -   a. coating a curable barrier coating composition which will cure        to form an impervious coating on the first major surface of the        open cell foam;    -   b. curing the curable barrier coating composition to provide an        impervious barrier coating;    -   c. applying a coating composition comprising abrasive particles        and curable binder curable to provide an abrasive coating over        the cured impervious barrier coating;    -   d. imparting a textured surface to the uncured coating        composition of step c;    -   e. curing the coating composition to provide a shaped abrasive        coating over the impervious barrier coating; and    -   f. perforating the impervious barrier coating and shaped        abrasive coating to provide the flexible abrasive product having        the foraminous barrier coating and the foraminous shaped        abrasive coating.

The invention further provides a method of finishing a surface of asubstrate, the method comprising the following steps:

-   -   a. contacting a surface of the substrate with a flexible        abrasive article comprising an open cell foam backing having a        first major surface and an opposite second major surface; a        foraminous barrier coating over said first major surface; and a        shaped foraminous abrasive coating over said foraminous barrier        coating comprised of abrasive particles in a binder; and    -   b. relatively moving said flexible abrasive article in the        presence of a liquid medium such as water to modify said surface        of said substrate.

Throughout this application, the following definitions apply:

A “flexible” abrasive article refers to an abrasive article that issufficiently flexible that it may be folded upon itself, yet on releasewill redeploy without permanent structural alterations to its originalconfiguration.

A “foraminous” barrier coating is a barrier coating that ischaracterized by having porosity sufficient to permit liquid passagetherethough.

A “shaped” abrasive coating refers to an abrasive coating comprised ofabrasive particles in a binder that has other than the typicaltopographic surface as may be encountered in conventional coatedabrasive products, but instead would have a textured surface havingraised portions and recessed portions which may be in an ordered or arandom pattern.

A shaped “foraminous” abrasive coating is a shaped abrasive coating thatis characterized by having porosity sufficient to permit liquid passagethroughout its area.

An “impervious” coating refers to a coating that has properties whichare the opposite of those of a foraminous coating, i.e., it hassubstantially no porosity which will permit liquid passage.

The various aspects of the invention will be better understood from thefollowing description of figures and the preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of one process for making aflexible abrasive article according to the present invention;

FIG. 2 is an enlarged schematic cross-sectional drawn representation ofa portion of a flexible abrasive product according to the presentinvention;

FIG. 3 is a photomicrograph taken at a magnification of 29× of the topsurface of a flexible coated abrasive product made in accordance withthe present invention.

FIG. 4 is a photomicrograph taken at a magnification of 97× of the topsurface of a flexible coated abrasive product made in accordance withthe present invention.

FIG. 5 is a photomicrograph taken at a magnification of 97× of the topsurface of an open cell foam backing used to make the flexible coatedabrasive product of the invention.

FIG. 6 is a photomicrograph taken at a magnification of 29× of the opencell foam backing shown in FIG. 5.

FIG. 7 is a photomicrograph taken at a magnification of 97× of the topsurface of a precursor to the flexible coated abrasive product of theinvention prior to being subjected to needle penetration.

FIG. 8 is a photomicrograph taken at a magnification of 97× of the topsurface of a flexible abrasive product made in accordance with thepresent invention resulting from needle penetration of the precursorshown in FIG. 7.

FIG. 9 is the precursor shown in FIG. 7, but at a magnification of 29×instead of 97×.

FIG. 10 is the product shown in FIG. 8, but at a magnification of 29×instead of 97×.

FIG. 11 is a top plan view of a roller for making a production tooluseful for making the shaped abrasive layer of articles according to thepresent invention.

FIG. 12 is an enlarged sectional view of a segment of the surface of theroller depicted in FIG. 11 taken at line 12-12 to show surface detail.

FIG. 13 is a top plan view of another roll useful for making aproduction tool to make the shaped abrasive layer of articles of thepresent invention.

FIG. 14 is an enlarged sectional view of one segment of the patternedsurface of the roll depicted in FIG. 13 taken at line 14-14.

FIG. 15 is an enlarged sectional view of another segment of thepatterned surface of the roll depicted in FIG. 13, taken at line 15-15.

FIG. 16 is an enlarged sectional view of a segment of flexible abrasiveproduct of the present invention comprising a convoluted open cell foambacking.

DETAILED DESCRIPTION OF THE INVENTION

The flexible abrasive product of the invention may be prepared bycoating an open cell foam backing with a barrier coating composition,e.g., by roll coating, spray coating or curtain coating, curing thebarrier coating composition, e.g., in a forced air oven heated at thecuring temperature of the barrier coating composition to provide thecoated backing bearing a foraminous barrier coating.

The barrier coated backing may be coated with an abrasive coatingaccording to the method described in U.S. Pat. No. 5,435,816 or U.S.Pat. No. 5,667,541, incorporated herein by reference. FIG. 1 illustratesan apparatus 10 for applying the shaped foraminous abrasive coating tothe barrier coated backing to provide an abrasive article according tothe invention. A production tool 11 is in the form of a belt having twomajor surfaces and two ends. An open cell foam backing 12 having a firstmajor surface 13 bearing a foraminous barrier coating and a second majorsurface 14 is unwound from roll 15. Open cell foam 12 is preferablyattached at its leading edge to a plastic film carrier (not shown) withsecond major surface 14 disposed on the film to provide dimensionalstability under tension to the open cell foam backing while it is beingcoated. Alternatively, open cell foam backing 12 is adhered on itssecond major surface 14 to one part of a two part attachment sheetmaterial to provide the dimensional stability to the open cell foambacking. Preferably it is adhered to the film-backed part which bearsthe engaging elements. At the same time open cell foam backing 12 isunwound from roll 15, the production tool 11 is unwound from roll 16.The contacting surface 17 of production tool 11 is coated with a mixtureof abrasive particles and binder precursor at coating station 18. Themixture can be heated to lower the viscosity thereof prior to thecoating step. The coating station 18 can comprise any conventionalcoating means, such as knife coater, drop die coater, curtain coater,vacuum die coater, or an extrusion die coater. After the contactingsurface 17 of production tool 11 is coated, the backing 12 and theproduction tool 11 are brought together such that the mixture wets thefirst major surface 13 of the backing 12. In FIG. 1, the mixture isforced into contact with the open cell foam backing 12 by means of acontact nip roll 20, which also forces the productiontool/mixture/backing construction against a support drum 22. Next, asufficient dose of radiation energy is transmitted by a source ofradiation energy 24 through the back surface 25 of production tool 11and into the mixture to at least partially cure the binder precursor,thereby forming a shaped, handleable structure 26. The production tool11 is then separated from the shaped, handleable structure 26.Separation of the production tool 11 from the shaped handleablestructure 26 occurs at roller 27. The angle α between the shaped,handleable structure 26 and the production tool 11 immediately afterpassing over roller 27 is preferably steep, e.g., in excess of 30°, inorder to bring about clean separation of the shaped, handleablestructure 26 from the production tool 11 except in the areas that werecoated over openings in the foraminous barrier coated open cell foambacking 12. The coating tends to adhere to the production tool surfacein these areas creating small openings in the abrasive coating whichcauses the abrasive coating to become foraminous. The production tool 11is rewound as roll 28 so that it can be reused. Shaped, handleablestructure 26 is wound as roll 30. If the binder precursor has not beenfully cured, it can then be fully cured by exposure to an additionalenergy source, such as a source of thermal energy or an additionalsource of radiation energy, to form the coated abrasive article.Alternatively, full cure may eventually result without the use of anadditional energy source to form the coated abrasive article. As usedherein, the phrase “full cure” and the like means that the binderprecursor is sufficiently cured so that the resulting product willfunction as an abrasive article, e.g. a coated abrasive article.

After the abrasive article is formed, it can be flexed and/or humidifiedprior to converting. The abrasive article can be converted into anydesired form such as a cone, endless belt, sheet, disc, etc. before use.

Referring now to FIG. 2, there is shown a flexible abrasive article 31which includes an open cell foam backing 12 that has a major surface 13and an opposite major surface 14. Major surface 13 is coated with aforaminous barrier coating 32 which, in turn in FIG. 2, is coated with ashaped foraminous abrasive coating 33 that is characterized by havingraised portions 34, depressions 35 and openings 36. While barriercoating 32 is shown in FIG. 2 as an integral single layer havingstraight defined surfaces, its bottom surface penetrates into thesurface of the open cell foam upon which it is coated, coating theindividual strands of the open cell foam within its structure. Openings36 in shaped foraminous abrasive coating 33 are characterized by beingover openings 37 in barrier coating 32 which are over openings 38 inmajor surface 13 of open cell foam backing 12. Openings 36 are typicallyirregular in shape because of the irregular nature of the openings inthe open cell foam backing 12, with few, if any, identical openings.This may be further appreciated by reference to FIGS. 3 and 4 of thedrawings.

FIGS. 7 and 9, respectively, show the top surface of a precursor productwhich may be perforated by needle penetration to provide the coatedabrasive product of the invention. FIGS. 8 and 10, respectively, showthe perforated product. It will be noted in FIGS. 8 and 10 that theopenings provided by the penetration of the needles causes the abrasivecoating to fracture to provide openings which do not correspond to theneedle shape but, in fact, are irregular with few openings beingidentical to each other. It is preferred that the needles only penetratethe foraminous layer and the shaped abrasive layer, but not the backinglayer, since it is already porous.

Foam Backing

In general, any open cell foam resilient backing with coatable surfaceson at least one surface may be used in the abrasive articles of theinvention. Such foams preferably have a sheet-like configuration withplanar major surfaces, although foams with one or both major surfacesbeing other than planar are also useful. Such surfaces may include aplurality of depressions or a plurality of projections whichrespectively may vary widely in depth, height, spacing, diameter andshape. Useful foam substrates have an elongation ranging from about 85to about 150% (i.e., the stretched length of the foam minus theunstretched length of the foam all divided by the unstretched length ofthe foam and then multiplied by 100 equals 85 to 150%.). Specificembodiments of the invention include open cell foam substrates havingelongation values of approximately 100 to 150%. The thickness of thefoam substrate is only limited by the desired end use of the abrasivearticle. Preferred foam substrates have a thickness in the range ofabout 1 mm to about 50 mm, although substrates having a greaterthickness can also be used.

The major surfaces of the open cell foam resilient backing may be eitherplanar or ordered nonplanar, i.e., they may be contoured into a regulararray of projecting portions and recessed portions as shown in FIG. 16.Such ordered nonplanar foams may be prepared by, e.g., the processdepicted in FIG. 8 of U.S. Pat. No. 5,396,737 (Englund and Schwartz),incorporated herein by reference. Foams containing ordered nonplanarsurfaces created by this process are sometimes referred to as“convoluted foams.” Ordered nonplanar foams may also be made by casting,molding, cutting, thermoforming, etc. The first and second majorsurfaces may both be planar, may both be ordered nonplanar, or maycomprise one planar and one ordered nonplanar surface. In the event thatan ordered nonplanar open cell foam backing is employed, an orderednonplanar first major surface and a generally planar second majorsurface is preferred. Ordered nonplanar surfaces may have projectingportions disposed in a regular rectangular or square array and/or mayinclude ridge portions extending between projecting portions. Therecessed portions can define a rectangular array of sockets with each ofthe sockets being bounded by ridges between four adjacent projectionportions. Projecting portions may extend from about 1 mm to about 65 mmfrom the opposite major surface. Recessed portions may extend from about0.5 mm to about 25 mm from the opposite major surface. The differencebetween the distance between a projecting portion and the opposite majorsurface and the distance between a recessed portion and the oppositemajor surface is from about 0.5 mm to about 64 mm.

FIG. 16 shows a segment 60 of a flexible abrasive product having an opencell foam backing 61 which has a planar back surface 62 to which isadhered an attachment means 63 (the hook part of a hook and loopfastener) by adhesive layer 64. The front face of backing 61 has anarray of projecting portions 65 and low portions 66. This surface iscovered with a foraminous coating 67 over which is coated a shapedforaminous abrasive coating 68.

The dimensions of a rectangular array of projecting portions andrecessed portions are somewhat dependent on the method by which thearray is produced. Preferably, the distance between adjacent projectingand recessed features is 0.03 to 40 mm, more preferably 1 mm to 25 mm,and most preferably 2 to 12 mm. Preferably, the distance betweenadjacent projecting portions is between 1.5 mm and 50 mm, morepreferably between 3 mm and 25 mm, and most preferably between 5 mm and15 mm.

The open cell foam backing of the flexible abrasive product of theinvention typically is in a sheet-like form most preferably with aminimum thickness of at least about 2 mm and preferably with a bulkdensity as determined by ASTM D-3574 of greater than about 0.03 gram percm³ (2 lbs per ft³). Useful embodiments of open cell foam backings havebulk densities of about 0.03 to about 0.10 grams per cm³ (1.8-6 lbs perft³). While thinner and/or lighter open cell foams may be useful, theymay require special handling because they are somewhat more difficult toprocess on conventional coating equipment. The open cell foam backingpreferably is formed of a foam having sufficient porosity to permit theentry of liquid water. The nature of the openings in the open cell foambacking may be appreciated by referring to FIGS. 5 and 6. A simple testfor air porosity will reveal whether the open cell foam has adequatewater permeability. The test for air porosity is accomplished accordingto ASTM D-3574 which test employs an air flow apparatus such as theFrazier™ differential pressure air permeability measuring instrument(low pressure model) manufactured by Frazier Instrument Company,Hagerstown, Md. Results are reported as cubic feet of air per minute persquare foot of sample at a pressure differential of 0.5 inch of water orcubic meters of air per minute per square meter of sample at a pressuredifference of 12.7 mm of water. Useful open cell foams have been foundto have an air permeability of at least 1 (0.305 m³/minute/m²),preferably from about 2 to about 50 (0.61 to 15.3 m³/minute/m²), mostpreferably from about 10 to about 60 ft³/minute/ft² at 0.5 inch pressuredifferential (3.05 to 18.3 m³/minute/m² at a pressure difference of 12.7mm of water). It should be noted that these air permeability valuesapply to the open cell foam after the barrier coat has been applied andto open cell foam sheets having a thickness in the range of about 90 toabout 188 mils (2.30 to 4.75 mm). The permeability values for open cellfoams without the barrier coating may be higher and for thicker foamsmay be lower.

The materials generally found to be useful to be made into the open cellfoam are organic polymers that are foamed or blown to produce porousorganic structures, which are typically referred to as foams. Such foamsmay be prepared from natural or synthetic rubber or other thermoplasticelastomers such as polyolefins, polyesters, polyamides, polyurethanes,and copolymers thereof, for example. Suitable synthetic thermoplasticelastomers include, but are not limited to, chloroprene rubbers,ethylene/propylene rubbers, butyl rubbers, polybutadienes,polyisoprenes, EPDM polymers, polyvinyl chlorides, polychloroprenes, orstyrene/butadiene copolymers. Particular examples of useful open cellfoams are polyester polyurethane foams, commercially available fromillbruck, Inc., Minneapolis, Minn. under the illbruck, Inc. tradedesignations R 200U, R 400U, R 600U and EF3-700C. Particular examples ofconvoluted open cell foams are polyester polyurethane foams,commercially available from illbruck, Inc. under the trade designationMINI-STANDARD CONVOLUTES.

Barrier Coating

Preferred barrier coating compositions comprise a suitable coatablematerial such as a polymer dissolved or dispersed as a latex, forexample, in a suitable liquid carrier material such as a solvent. Suchcompositions preferably are easily coated onto one major surface of theopen cell foam substrate and, once coated, cured to provide a foraminouscoating or a nonforaminous barrier coating that will later beperforated. Suitable materials for forming the foraminous barriercoating are acrylic latex emulsions that will coat the surface of theopen cell foam backing without blocking the pores so that porosityremains after curing. A preferred composition for forming the foraminousbarrier coating is an acrylic emulsion available from BF Goodrich,Cleveland, Ohio under the trade designation HyCar™ 2679 latex. The drycoating weight of barrier coating applied to the open cell foampreferably is at least 50 grams per square meter (gsm) and typically mayvary between 65 gsm and 180 gsm.

Useful barrier coats which cure to provide an impervious coating whichis later perforated to make it foraminous include an acrylic latex(e.g., HyCar™ 2679) which has been thickened to provide a coatingcomposition that will not readily penetrate the open cell foam backingbut instead will remain a surface layer which will cure to provide theimpervious barrier coating. The acrylic emulsion is thickened by theaddition of a thickening agent such as solution of a polyacrylic acidavailable under the trade designation Carbopol™ EZ-1 from BF Goodrichwhich has been thickened by the addition of an aqueous ammoniumhydroxide solution which serves as an activator for the Carbopol™ EZ-1polyacrylic acid solution. The dry coat weight of the barrier coatingwhich will cure to provide an impervious coating is preferably at least150 gsm and typically may vary between about 160 to 190 gsm. Aftercuring, the impervious barrier coating is overcoated with a shapedcoating comprised of curable binder and abrasive particles, which isthen cured. Such coatings may be made foraminous by perforating thecured coatings preferably from the abrasive side with a staggered 20×20array of needles (Foster™ 15×18×25×3.5 RB) deployed in a standard needleboard with rows and columns being spaced ½ inch (1 cm) apart andoperated at 37 strokes per 10 inch (25 cm) length to provide about 148penetrations per square inch (about 6.5 cm²). Such needles and a needleboard may be obtained from Foster Needle Company, Inc., Manitowoc, Wis.

Shaped Abrasive Coating

The shaped foraminous abrasive coating is formed by providing a slurryof fine abrasive particles in a curable binder system.

As previously mentioned, the shaped foraminous abrasive coating ispreferably made according to the method described in commonly assignedU.S. Pat. No. 5,435,816 (Spurgeon, et al.). Any of a variety of methodsof forming a shaped coated abrasive coating may be employed to beapplied to the impervious barrier coating. Such methods include, forexample, that disclosed in Spurgeon, et al. in U.S. Pat. No. 5,435,816,that disclosed in Christianson, et al. in U.S. Pat. No. 5,910,471, thatdisclosed in Bruxvoort, et al. in U.S. Pat. No. 5,958,794, thatdisclosed in Pieper, et al., in U.S. Pat. No. 5,152,917 and thatdisclosed in Ravipati, et al., in U.S. Pat. No. 5,014,468, each of thesepatents being incorporated herein by reference.

In the event that ordered nonplanar open cell foam backings havingprojecting and recessed portions on a first major surface (“front”surface), the coating conditions are maintained such that when theproduction tool is applied to the projecting and recessed areas they aremomentarily compressed into a planar configuration. Upon subsequentrelease of the compression, the projecting and recessed portionsrecover. Such momentary compression results in uniform coatings andshaped abrasive coatings having shaped features that are oriented normalto the surfaces of the various projecting and recessed areas.

The coatable composition which is curable to provide a shaped abrasivecoating is then applied to the impervious barrier coating by a techniquewhich imparts a texture to the abrasive layer to provide the shapedabrasive coating on curing. The shaped abrasive coating and imperviousbarrier coating over the open cell foam backing are then perforated byuse of a suitable needle board to provide the necessary porosity throughthe abrasive article. Perforation is preferably from front (the abrasiveside) to back to avoid discontinuities in the abrasive coating. Theopenings in a perforated shaped foraminous abrasive coating arecharacterized by being in a regular pattern, i.e., corresponding to thepattern of the needle board and web traverse which was used to formthem, although the openings themselves are somewhat irregular in shapedue to the fracturing of the abrasive coating as it is penetrated by theneedles.

The mixture to be used to form the shaped abrasive coating, in eithercase, for application to a foraminous barrier coated open cell foam orto an impervious barrier coated open cell foam, comprises a plurality ofabrasive particles dispersed in a binder precursor sometimes referred toas a curable binder. As used herein, the term “mixture” means anycomposition comprising a plurality of abrasive particles dispersed in abinder precursor. It is preferred that the mixture be flowable. However,if the mixture is not flowable, it can be extruded or forced by othermeans, e.g. heat or pressure or both, onto the contacting surface of theproduction tool or onto the front surface of the backing. The mixturecan be characterized as being conformable, that is, it can be forced totake on the same shape, outline, or contour as the contacting surface ofthe production tool and the front surface of the open cell foam backing.

The abrasive particles typically have an average particle size rangingfrom about 0.1 to 1500 micrometers, usually from about 1 to 400micrometers. It is preferred that the abrasive particles have a Mohs'hardness of at least about 8, more preferably above 9. However, theparticles may have a Mohs' hardness value lower than 8 depending onintended use. Examples of abrasive particles suitable for use in thisinvention include fused aluminum oxide, ceramic aluminum oxide, heattreated aluminum oxide, white aluminum oxide, green silicon carbide,silicon carbide, alumina zirconia, diamond, ceria, cubic boron nitride,garnet, and combinations thereof. The phrase “abrasive particles”includes both individual abrasive grits and a plurality of individualabrasive grits bonded together to form an agglomerate. Abrasiveagglomerates are further described in U.S. Pat. Nos. 4,311,489;4,652,275; and 4,799,939, incorporated herein by reference.

The binder precursor is capable of being cured by energy, preferablyradiation energy, more preferably, radiation energy from ultravioletlight, visible light, or electron beam sources. Other sources of energyinclude infrared, thermal, and microwave. It is preferred that theenergy not adversely affect the production tool used in the method ofthe invention, so that the tool can be reused. The binder precursor canpolymerize via a free radical mechanism or a cationic mechanism.Examples of binder precursors that are capable of being polymerized byexposure to radiation energy include acrylated urethanes, acrylatedepoxies, ethylenically unsaturated compounds, aminoplast derivativeshaving pendant unsaturated carbonyl groups, isocyanurate derivativeshaving at least one pendant acrylate group, isocyanate derivativeshaving at least one pendant acrylate group, vinyl ethers, epoxy resins,and combinations thereof. The term “acrylate” includes acrylates andmethacrylates.

Acrylated urethanes are diacrylate esters of hydroxy terminated NCOextended polyesters or polyethers. Examples of commercially availableacrylated urethanes include that available under the trade name“UVITHANE™ 782,” from Morton Thiokol Chemical, and those available underthe trade designations “CMD 6600,” “CMD 8400,” and “CMD 8805,” fromRadcure Specialties.

Acrylated epoxies are diacrylate esters of epoxy resins, such as thediacrylate esters of bisphenol A epoxy resin. Examples of commerciallyavailable acrylated epoxies include those available under the tradedesignations “CMD 3500,” “CMD 3600,” and “CMD 3700,” from RadcureSpecialties.

Ethylenically unsaturated compounds include both monomeric and polymericcompounds that contain atoms of carbon, hydrogen, and oxygen, andoptionally, nitrogen and the halogens. Oxygen or nitrogen atoms or bothare generally present in ether, ester, urethane, amide, and urea groups.Ethylenically unsaturated compounds preferably have a molecular weightof less than about 4,000. The preferred ethylenically unsaturatedcompounds are esters made from the reaction of compounds containingaliphatic monohydroxy groups or aliphatic polyhydroxy groups andunsaturated carboxylic acids, such as acrylic acid, methacrylic acid,itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and thelike. Representative examples of ethylenically unsaturated compoundsinclude methyl methacrylate, ethyl methacrylate, styrene,divinylbenzene, vinyl toluene, ethylene glycol diacrylate, ethyleneglycol methacrylate, hexanediol diacrylate, triethylene glycoldiacrylate, trimethylopropane triacrylate, glycerol triacrylate,pentaerythritol triacrylate, pentaerythritol methacrylate, andpentaerythritol tetraacrylate. Other ethylenically unsaturated compoundsinclude monoallyl, polyallyl, and polymethallyl esters and amides ofcarboxylic acids, such as diallyl phthalate, diallyl adipate, andN,N-diallyladipamide. Still other nitrogen-containing ethylenicallyunsaturated compounds include tris (2-acryloyloxyethyl)isocyanurate,1,3,5-tri(2-methyacryloxyethy)-s-triazine, acrylamide, methylacrylamide,N-methylacrylamide, N,N-dimethylacrylamide, N-vinylpyrrolidone, andN-vinylpiperidone.

Aminoplast resins suitable for this invention have at least one pendantα,β-unsaturated carbonyl group per molecule or oligomer. These materialsare further described in U.S. Pat. No. 4,903,440 and U.S. Pat. No.5,236,472, both of which are incorporated herein by reference.

Isocyanurate derivatives having at least one pendant acrylate group andisocyanate derivatives having at least one pendant acrylate group arefurther described in U.S. Pat. No. 4,652,275, incorporated herein byreference. The preferred isocyanurate derivative is a tri-acrylate oftris(hydroxy ethyl)isocyanurate.

Epoxy resins have an oxirane ring and are polymerized by opening of thering. Epoxy resins suitable for this invention include monomeric epoxyresins and oligomeric epoxy resins. Representative examples of epoxyresins preferred for this invention include2,2-bis[4-(2,3-epoxypropoxy)phenylpropane](diglycidyl ether ofbisphenol) and commercially available materials under the tradedesignation “Epon™ 828,” “Epon™ 1004,” and “Epon™ 1001F,” available fromShell Chemical Co., under the trade designations “DER™-331,” “DER™-332,”and “DER™-334,” available from Dow Chemical Co. Other epoxy resinssuitable for this invention include glycidyl ethers of phenolformaldehyde novolac (e.g., under the trade designations “DEN™-431” and“DEN™-428,” available from Dow Chemical Co.). Epoxy resins useful inthis invention can polymerize via a cationic mechanism in the presenceof one or more appropriate photoinitiators. These resins are furtherdescribed in U.S. Pat. No. 4,318,766, incorporated herein by reference.

If either ultraviolet radiation or visible radiation is to be used, itis preferred that the binder precursor further comprise aphotoinitiator. Examples of photoinitiators that generate a free radicalsource include, but are not limited to, organic peroxides, azocompounds, quinones, benzophenones, nitroso compounds, acyl halides,hydrazones, mercapto compounds, pyrylium compounds, triacrylimidazoles,bisimidazoles, phosphene oxides, chloroalkyltriazines, benzoin ethers,benzil ketals, thioxanthones, acetophenone derivatives, and combinationsthereof.

Cationic photoinitiators generate an acid source to initiate thepolymerization of an epoxy resin. Cationic photoinitiators can include asalt having an onium cation and a halogen containing a complex anion ofa metal or metalloid. Other cationic photoinitiators include a salthaving an organometallic complex cation and a halogen containing complexanion of a metal or metalloid. These are further described in U.S. Pat.No. 4,751,138, incorporated herein by reference. Another example of acationic photoinitiator is an organometallic salt and an onium saltdescribed in U.S. Pat. No. 4,985,340; European Patent Applications306,161; 306,162; all of which are incorporated herein by reference.Still other cationic photoinitiators include an ionic salt of anorganometallic complex in which the metal is selected from the elementsof Periodic Group IVB, VB, VIB, VIIB and VIIIB.

In addition to the radiation curable resins, the binder precursor mayfurther comprise resins that are curable by sources of energy other thanradiation energy, such as condensation curable resins. Examples of suchcondensation curable resins include phenolic resins,melamine-formaldehyde resins, and urea-formaldehyde resins.

The binder precursor can further comprise optional additives, such as,for example, fillers (including grinding aids), fibers, lubricants,wetting agents, surfactants, pigments, dyes, coupling agents,plasticizers, and suspending agents. An example of an additive to aid inflow properties has the trade designation “OX-50,” commerciallyavailable from DeGussa. The amounts of these materials can be adjustedto provide the properties desired. Examples of fillers include calciumcarbonate, silica, quartz, aluminum sulfate, clay, dolomite, calciummetasilicate, and combinations thereof. Examples of grinding aidsinclude potassium tetrafluoroborate, cryolite, sulfur, iron pyrites,graphite, sodium chloride, and combinations thereof. The mixture cancontain up to 70% by weight filler or grinding aid, typically up to 40%by weight, and preferably from 1 to 10% by weight, most preferably from1 to 5% by weight.

A preferred mixture for making the abrasive coating for the products ofthe present invention comprises 19.47 parts by weight trimethylolpropanetriacrylate available under the trade designation SR 351 from SartomerCompany, Exton, Pa., 12.94 parts by weight 2-phenoxyethyl acrylateavailable under the trade designation SR 339 from Sartomer Company, 3.08parts by weight dispersant available under the trade name Zephrym™ PD9000, 1.08 part by weight ethyl 2,4,6-trimethylbenzoylphenyl-phosphinateavailable under the former trade designation Lucirin™ LR 8893 (now underthe trade designation Lucirin™ TPO-L) from BASF as a photoinitiator,1.93 part by weight gamma-methacryloxypropyltrimethoxy silane availableunder the trade designation Silquest™ A—174™ Silane from Witco, Corp.,Greenwich, Conn., as a resin modifier and 61.50 parts by weight grade GC3000 green silicon carbide abrasive particles having an average particlesize of 4.0 μm available from Fujimi Abrasives Company, based on 100.00parts by weight total.

The mixture can be prepared by mixing the ingredients, preferably by alow shear mixer. A high shear mixer can also be used. Typically, theabrasive particles are gradually added into the binder precursor.Additionally, it is possible to minimize the amount of air bubbles inthe mixture. This can be accomplished by pulling a vacuum during themixing step.

During the manufacture of the shaped, handleable structure, radiationenergy is transmitted through the production tool and into the mixtureto at least partially cure the binder precursor. The phrase “partialcure” means that the binder precursor is polymerized to such a statethat the resulting mixture releases from the production tool. The binderprecursor can be fully cured once it is removed from the production toolby any energy source, such as, for example, thermal energy or radiationenergy. The binder precursor can also be fully cured before the shaped,handleable structure is removed from the production tool.

Sources of radiation energy preferred for this invention includeelectron beam, ultraviolet light, and visible light. Other sources ofradiation energy include infrared and microwave. Thermal energy can alsobe used. Electron beam radiation, which is also known as ionizingradiation, can be used at a dosage of about 0.1 to about 10 Mrad,preferably at a dosage of about 1 to about 10 Mrad. Ultravioletradiation refers to non-particulate radiation having a wavelength,within the range of about 200 to 400 nanometers, preferably within therange of about 250 to 400 nanometers. It is preferred that ultravioletradiation be provided by ultraviolet lamps operating in a range of 100to 300 Watts/cm. Visible radiation refers to non-particulate radiationhaving a wavelength within the range of about 400 to about 800nanometers, preferably within the range of about 400 to about 550nanometers.

In the method of this invention, the radiation energy is transmittedthrough the production tool and directly into the mixture. It ispreferred that the material from which the production tool is made notabsorb an appreciable amount of radiation energy or be degraded byradiation energy. For example, if electron beam energy is used, it ispreferred that the production tool not be made from a cellulosicmaterial, because the electrons will degrade the cellulose. Ifultraviolet radiation or visible radiation is used, the production toolmaterial should transmit sufficient ultraviolet or visible radiation,respectively, to bring about the desired level of cure.

The production tool should be operated at a velocity that is sufficientto avoid degradation by the source of radiation. Production tools thathave relatively high resistance to degradation by the source ofradiation can be operated at relatively lower velocities; productiontools that have relatively low resistance to degradation by the sourceof radiation can be operated at relatively higher velocities. In short,the appropriate velocity for the production tool depends on the materialfrom which the production tool is made.

The production tool can be in the form of a belt, e.g., an endless belt,a sheet, a continuous sheet or web, a coating roll, a sleeve mounted ona coating roll, or die. The surface of the production tool that willcome into contact with the mixture has a topography or pattern. Thissurface is referred to herein as the “contacting surface.” If theproduction tool is in the form of a belt, sheet, web, or sleeve, it willhave a contacting surface and a non-contacting surface. If theproduction tool is in the form of a coating roll, it will have acontacting surface only. The topography of the abrasive article formedby the method of this invention will have the inverse of the pattern ofthe contacting surface of the production tool. The pattern of thecontacting surface of the production tool will generally becharacterized by a plurality of cavities or recesses. The opening ofthese cavities can have any shape, regular or irregular, such as arectangle, semicircle, circle, triangle, square, hexagon, octagon, etc.The walls of the cavities can be vertical or tapered. The pattern formedby the cavities can be arranged according to a specified plan or can berandom. The cavities can butt up against one another.

Thermoplastic materials that can be used to construct the productiontool include polyesters, polycarbonates, poly(ether sulfone),poly(methyl methacrylate), polyurethanes, polyvinylchloride,polyolefins, polystyrene, or combinations thereof. Thermoplasticmaterials can include additives such as plasticizers, free radicalscavengers or stabilizers, thermal stabilizers, antioxicants, andultraviolet radiation absorbers. These materials are substantiallytransparent to ultraviolet and visible radiation. One type of productiontool is described in U.S. Pat. No. 5,435,816. Examples of materialsforming the production tool include polycarbonate and polyester. Thematerial forming the production tool should exhibit low surface energy.The material of low surface energy improves ease of release of theabrasive article from the production tool. Examples of materialssuitable include polypropylene and polyethylene. In some productiontools made of thermoplastic material, the operating conditions formaking the abrasive article should be set such that excessive heat isnot generated. If excessive heat is generated, this may distort or meltthe thermoplastic tooling. In some instances, ultraviolet lightgenerates heat. It should also be noted that a tool consisting of asingle layer is also acceptable, and is the tool of choice in manyinstances. A thermoplastic production tool can be made according to theprocedure described in U.S. Pat. No. 5,435,816.

FIG. 11 shows a roller 40 that was used for making production tool 11 asdepicted in FIG. 1. The following specific embodiment of roller 40 wasused to make production tool 11 which was then used to make Examples 1-6of the invention. Roller 40 has a shaft 41, an axis of rotation 42 and apatterned surface 43 over a major portion of its cylindrical surface.The length of the patterned surface is d which may vary according to theuser's requirements. The patterned surface 43 includes 2 identical sets44 and 45 of repeating equally spaced grooves, with grooves in set 44being deployed in a direction perpendicular to grooves in set 45 withangle c being 90°. In this embodiment angle a is 50° with respect to theaxis of rotation 42 and angle b is 40° with respect to the axis ofrotation.

FIG. 12 provides an enlarged cross sectional view of a segment ofpatterned surface 43 taken at line 12-12 in FIG. 11 perpendicular to oneset of grooves. In this case, the peak to peak distance, l, is 0.0042inch (0.107 mm) and the valley to peak distance, n, is 0.025 inch (0.064mm). The angle between adjacent peak slopes, m, is 80°.

Roller 40 was used to make a production tool of the type described aboveto impart a shaped surface to the abrasive articles depicted in FIGS. 3,4 and 7-10.

An alternative roller 50 is depicted in FIG. 13 which includes a shaft51 and an axis of rotation 52. In this case the patterned surfaceincludes a first set 53 of adjacent circumferential grooves around theroller and a second set 54 of equally spaced grooves deployed at anangle of 30° with respect to the axis of rotation 52.

FIG. 14 shows an enlarged cross sectional view of a segment of thepatterned surface of roller 50 taken at line 14-14 in FIG. 13perpendicular to the grooves in set 53. FIG. 14 shows the patternedsurface has peaks spaced by distance x which is 50 μm apart peak to peakand a peak height, y, from valley to peak of 50 μm, with an angle zwhich is 53° angle between adjacent peak slopes.

FIG. 15 shows an enlarged cross sectional view of a segment of thepatterned surface of roller 50 taken at line 15-15 in FIG. 13perpendicular to the grooves in set 54. FIG. 15 shows grooves 55 havingan angle w which is a 90° angle between adjacent peak slopes and valleysseparated by a distance t which is 250 μm and a valley depth s which is55 μm.

Roller 50 is also useful for producing a preferred production tool foruse in the process depicted in FIG. 1.

The flexible abrasive product of the present invention is typically usedin surface finishing applications with a sanding device such as a dualaction sander. A useful dual action sander is that sold by DynabradeInc. of Clarence, N.Y. under the trade designation Dynorbital™ sandermodel number 56964. Such a sander typically requires a sanding padhaving a surface to which the flexible abrasive product of the inventionwill be mounted. A preferred pad surface typically includes one part ofa two part attachment surface such as a looped fabric to which a backingbearing hooks or flattened stems on the backside of the abrasive productwill engage. A preferred backing for this purpose is known under thetrade designation Hookit™ II laminating backing made available inabrasive products sold, for example, under the trade designation 3MHookit™ II Finishing Film Discs by Minnesota Mining and ManufacturingCompany, St. Paul, Minn.

Workpiece

The workpiece can be any of a variety of types of material such aspainted surfaces (clear coat, base (color) coat, primer or e-primer)coated surfaces (polyurethane, lacquer, etc), plastics (thermoplastic,thermosetting), reinforced plastics, metal, (carbon steel, brass,copper, mild steel, stainless steel, titanium and the like) metalalloys, ceramics, glass, wood, wood-like materials, composites, stones(including gem stones), stone-like materials, and combinations thereof.The workpiece may be flat or may have a shape or contour associated withit. Examples of common workpieces that may be polished by the abrasivearticle of the invention include painted automotive surfaces (car doors,hoods, trunks, etc.), plastic automotive components (headlamp covers,tail-lamp covers, other lamp covers, arm rests, instrument panels,bumpers, etc.), flooring (vinyl, stone, wood and wood-like materials),counter tops, other plastic components and the like.

Depending upon the application, the force load at the polishinginterface may range from about 0.01 kg to over 25 kg. Generally, thisrange is between 1 kg to 15 kg of force load at the polishing interface.Also, it is preferred to have a liquid present during polishing. Theliquid may be water and/or an organic compound. These liquids may alsocontain other additives such as defoamers, degreasers, lubricants,soaps, corrosion inhibitors, or the like. The abrasive article mayoscillate at the abrading interface during use.

At least one or both of the abrasive article and the workpiece is movedrelative to the other. The abrasive disc may range from about 50 mm to1,000 mm in diameter. Typically, abrasive discs are secured to a back-uppad by an attachment means. The attachment means may be a hook and looptype attachment, where the hooks may be on the back side of the abrasivearticle and the loops on the support pad or vice versa. Alternatively,the attachment system may be a pressure sensitive adhesive. The abrasivediscs typically rotate between 100 to 20,000 revolutions per minute,usually between 1,000 to 10,000 revolutions per minute. The back up padmay rotate in a circular fashion, orbital fashion or random orbitalfashion. Alternatively, the abrasive article of the invention may beused by hand.

EXAMPLES

The invention is further illustrated by the following examples whereinall parts and percentages are by weight unless otherwise indicated.

Identification of Ingredients

“HyCar™ 2679” is an acrylic latex obtained from BF Goodrich SpecialtyChemicals, Inc., Cleveland, Ohio containing about 50% by weight acrylicpolymer solids in an aqueous medium which includes trace quantities offormaldehyde.

“Carbopol™ EZ-1” is an acrylic resin powder comprised of crosslinkedacrylic acid polymer used as a thickener obtained from BF GoodrichSpecialty Chemicals, Inc., Cleveland, Ohio.

“Ammonium Hydroxide Solution” is an aqueous solution of ammoniumhydroxide containing 29.5% by weight NH₃.

“3M Fluorad™ Fluorosurfactant FC-129” is an anionic surfactantconsisting of 50% by weight potassium fluoroalkyl carboxylates dissolvedin 14% by weight 2-butoxyethanol, 4% by weight ethyl alcohol and 32% byweight water obtained from Minnesota Mining and Manufacturing Company(3M) of St. Paul, Minn.

“Hookit™ II Laminating Backing” is one part of a 2-part fastening systemcomprising sheet material bearing on one side a multiplicity of erectstems that have flattened distal ends that is made according to U.S.Pat. No. 5,667,540 and manufactured by 3M Company of St. Paul, Minn. Theflattened stems are engageable in a fabric material which provides theother part of 2-part fastening system, as described in U.S. Pat. No.5,962,102. The Hookit™ II laminating backing is mounted on the backsideof an abrasive pad by an adhesive coating on its backside which isbrought into contact with the backside of the abrasive pad.

“SR 351” is trimethylolpropane triacrylate monomer having a molecularweight of 296 and functionality of 3 available under the designationSR—351 from Sartomer Company, Exton, Pa.

“SR 339” is 2-Phenoxyethyl acrylate aromatic monomer having a molecularweight of 192 and functionality of 1 available under the designationSR—339 from Sartomer Company, Exton, Pa.

“PD 9000” is a polymeric disperant available under the trade designationZephrym™ PD 9000 (formerly known as Hypermer PS-4) from Uniqema aninternational business of Imperial Chemical Industries PLC.

“A—174™” is gamma-methacryloxypropyltrimethoxy silane resin modifieravailable under the trade designation SILQUEST™ A—174™ silane from WitcoCorporation, Greenwich, Conn.

“TPO-L” is ethyl 2,4,6-trimethylbenzoylphenylphosphinate photoinitiatoravailable under the trade designation LUCIRIN™ TPO-L (formerly known asLUCIRIN™ LR 8893) from BASF Corp., Charlotte, N.C.

“Green SiC” is green silicon carbide abrasive particles having a gradesize of GC 3000 and an average particle size of 4.0 μm as determined byCoulter™ Counter available under the trade designation FUJIMI GC 3000from Fujimi Abrasives Company, Elmhurst, Ill.

Table 1 shows the trade designations for open cell polyesterpolyurethane foams obtained from illbruck, Inc., Minneapolis, Minn.:TABLE 1 Bulk Density Tensile Strength Elongation Designation (lb/ft³)(kg/m³) (psi) (kg/cm²) (%) “R 200U” 1.8-2.0 29-32 19.0 1.3 100 “R 400U”4.0 ± 0.4 64 ± 6  20.0 1.4 100 “R 600U” 6.0 ± 0.6 96 ± 10 16.0 1.1 150“PPF 8” 2.2-2.7 34-38 66.1 4.6 173

“EF3-700C” is the trade designation of illbruck, Inc., Minneapolis,Minn. for a felted, polyether foam felted at a ratio of 3:1 to itsthickness. The EF3-700C foam has a bulk density of 1.65-1.9 lb/ft³(26-30 kg/m³), a tensile strength of 12 psi (0.8 kg/cm²), an elongationof 85%.

The air permeability values of various open cell foam samples, bothuncoated and coated with a barrier coat, were determined by use of theFrazier™ air permeability measuring instrument described above. Thesevalues are set forth in Table 2. TABLE 2 Coating Weight PermeabilityManufacturer's Dry Hycar ™ Ft³ Air/Min/Ft² M³ Air/Min/M² Product 2679Grain Dry Hycar ™ Coat of Sample @ of Sample @ Code 4 × 6¹ 2679 gsmMethod 0.5″ Water 12.7 mm Water EF3-700C-188 13.9 58.2 Roll 17. 5.92EF3-700C-188 14.5 60.7 Roll 14.6 5.08 EF3-700C-188 15.9 66.5 Roll 10.3.48 EF3-700C-188 16.3 68.2 Roll 11.8 4.11 EF3-700C-188 20.0 83.7 Roll8. 2.78 EF3-700C-188 22.1 92.5 Roll 11.8 4.11 EF3-700C-188 22.5 94.2Roll 8.1 2.82 EF3-700C-188 23.4 97.9 Spray 15.7 5.46 EF3-700C-188 23.497.9 Spray 16.8 5.85 EF3-700C-188 24.0 100.4 Roll 6.7 2.33 EF3-700C-18824.0 100.4 Roll 6.6 2.30 EF3-700C-188 24.4 102.1 Roll 6.7 2.33EF3-700C-188 25.0 104.6 Roll 8.9 3.10 EF3-700C-188² 42.0 175.8 Knife0.143 0.05 EF3-700C-188 None None 14.9 5.19 EF3-700C-188 None None 14.95.19 EF3-700C-188 None None 16.8 5.85 R200U-188 37.6 157.4 Roll 111.38.63 R200U-188 39.2 164.1 Roll 113. 39.32 R200U-188 41.8 174.9 Roll 98.34.10 R200U-188 None None 434. 151.03 R400U-188 15.9 66.5 Spray 13.84.80 R400U-188 15.9 66.5 Spray 22.2 7.73 R400U-188 23.4 97.9 Spray 28.19.78 R400U-188 23.4 97.9 Spray 18.1 6.30 R400U-188 23.9 100.0 Roll 17.25.99 R400U-188 27.5 115.1 Roll 18.9 6.58 R400U-188 29.4 123.0 Roll 18.46.40 R400U-188 None None 22.5 7.83 R600U-090 15.9 66.5 Spray 20.2 7.03R600U-090 23.4 97.9 Spray 39.8 13.85 R600U-090 23.4 97.9 Spray 31.510.96 R600U-090 41.5 173.7 Roll 81. 28.19 R600U-090 45.1 188.7 Roll 90.31.32 R600U-090 51.1 213.9 Roll 90. 31.32 R600U-090 None None 214. 74.47R600U-125 15.9 66.5 Spray 13.3 4.63 R600U-125 15.9 66.5 Spray 16.6 5.78R600U-125 23.4 97.9 Spray 12.6 4.38 R600U-125 34.1 142.7 Roll 44.7 15.56R600U-125 34.5 144.4 Roll 55.1 19.17 R600U-125 37.3 156.1 Roll 54.418.93 R600U-125 None None 114. 39.67 R600U-188 40.9 171.2 Roll 12.7 4.42R600U-188 41.8 174.9 Roll 41.4 14.41 R600U-188 42.6 178.3 Roll 55.719.38 R600U-188 43.1 180.4 Roll 41.5 14.44 R600U-188 45.6 190.8 Roll 35.12.18 R600U-188 None None 189. 65.77¹The test sample was 4 inches by 6 inches (about 5 cm by 7.5 cm).²Open cell foam was coated with an impervious barrier coat.

Examples 1-6 and Comparative Examples A-C

Examples 1-6 and Comparative Examples A-C demonstrate the advantages ofthe inventive abrasive articles when employed to refine the surface ofpainted automotive panels. The compositions of Examples 1-6 andComparative Example A are shown in Table 3.

A barrier coating composition consisting of 100% HYCAR™ 2679 wasemployed in the roll coating and spray coating processes to makeforaminous barrier coatings. When the knife coating process wasemployed, a thickened barrier coating composition further consisting of91.120% HYCAR™ 2679, 5.304% water, 0.152% FLUORAD™ FC 129, 3.152%CARBOPOL™ EZ-1 (4% in water), and 0.273% ammonium hydroxide solution wasused to apply an impervious barrier coating. The selected barriercoating composition was applied to each foam backing by either a rollcoating process, a spray coating process, or a knife coating process asindicated in Table 3.

The roll coating process was used to generate a foraminous barrier coatand employed 7.6 cm diameter rolls (one with a rubber surface and onewith a steel surface) gapped to about 0.38 mm less than the thickness ofthe foam to be coated. The coating pan was filled with the barriercoating composition and the coater set to operate at 3 to 4.5 m/min. Thevarious foam backing sheets (1 m×0.3 m) were then introduced into thenip. Upon exiting the nip area, each coated backing was impinged by anair flow to break any bubbles resulting from the coater. The sheets werethen placed in an oven set at 120-150° C. for about 6 minutes.

The spray coating process was used to generate a foraminous barrier coatand employed a conveyor belt traversing under a reciprocating spraynozzle and subsequent radiant heater sufficient to achieve a temperatureat the backing surface of about 120° C. The conveyor speed wascontrolled to provide the required add-on as reported in Table 3.

The knife coating process was used to generate impervious barriercoatings on selected backings. The 1 m×0.3 m foam backing specimens weredrawn by hand at about 10 m/minute through a knife coater having thecoating knife adjusted to barely touch the backing surface. Anapproximate 50 ml aliquot of thickened barrier coating composition wasplaced before the leading edge of the knife. The knife position wasadjusted to achieve the required add-on. The coated backing was thenplaced in an oven set at 150° C. for about 6 minutes.

After the appropriate barrier coating was applied, an abrasive slurryformed by mixing 19.47 parts SR 351, 12.94 parts SR 339, 3.08 parts PD9000, 1.93 part A-174™, 1.08 part TPO-L, and 61.50 parts Green SiC wasapplied. The slurry was applied via knife coating to a polypropylenetool having a patterned surface, the patterned surface being the reversepattern of that desired for the shaped abrasive surface, and being madeby use of a pattern roll depicted in FIGS. 11 and 12. The coated toolwas then applied to the coated foam backing so that contact isestablished between the coating of the backing and the slurry side ofthe tool. The tool side of the resulting lamination was then exposed toultraviolet radiation by exposure to a D-bulb at high power (600 Wattsper inch) (236 Watts per cm) while moving the web at 30 feet per minute(9.14 m/minute) at a nip pressure of 50 psi (3.52 kg/cm²) for a 10 inch(25 cm) wide web. The tooling was then removed from the resultingpartially-cured shaped abrasive coating on the barrier coated backing.In the event that the barrier coating was foraminous, this process ofremoving the tool caused at least part of the shaped abrasive layer inat least some of the tool cavities to remain in the polypropylene tool,thereby creating a shaped abrasive layer with irregular openings.Alternatively, in the case of the barrier coating being impervious, atleast most of the shaped abrasive layer was successfully transferredfrom the tool cavities to the barrier coating, thereby creating a moreuniform shaped abrasive layer.

Example 6 was further needle tacked to render foraminous the otherwiseimpervious barrier coated article. The abrasive composition was needledfrom the abrasive side with a staggered 20×20 array of needles (Foster15×18×25×3.5 RB) deployed in a standard needle board with rows andcolumns being spaced ½ inch (1 cm) apart and operated at 37 strokes per10 inch (25 cm) length (1.46 stroke per cm) to provide about 148penetrations per square inch (23 penetrations per cm²). Such needles andneedle board may be obtained from Foster Needle Company, Inc.,Manitowoc, Wis. Needle tacking provided the requisite porosity for thesuccessful employment of the otherwise unacceptable abrasive article, asindicated by comparison with Comparative Example A, that is identical toExample 6, but without the needling step.

The resulting abrasive products were then ready for conversion to sixinch (15 cm) diameter discs for comparative testing.

Examples 7-9

Examples 7-9 demonstrate the preparation and efficacious performance ofabrasive articles of the present invention when made using convolutedopen cell foam backings.

Examples 7-9 were made according to the procedure described for Examples1-6 employing roll coating to provide the barrier coating except for theuse of a production tool having a different geometry from that of theprevious examples. Example 7 used a polyester polyurethane open cellfoam backing with planar major surfaces available from illbruck, Inc. as“R600U-090.” Examples 8 and 9 used a convoluted polyester polyurethaneopen cell foams “PPF8” and “R400U,” respectively, having an array of 20mm base diameter, 2 mm high projecting portions on the first majorsurface spaced 25 mm apart, and a thickness measured from the distalends of the projection on the first major surface to the second majorsurface of 5 mm. The second major surface was essentially planar. Theconvoluted foam for Examples 8 and 9 was obtained from illbruck underthe illbruck designation “Mini-Standard.” Examples 7-9 are furtherdescribed in Table 3. Comparative test results are reported in Table 4.TABLE 3 Barrier Shaped Coating Abrasive Barrier wt, g/m² Coating ExampleFoam Backing Coat (dry) wt, g/m² Needled 1 EF3-700C-188 Roll coat100-121 66 No 2 R600U-125 Spray coat 98 60-67 No 3 R600U-90 Spray coat67 60-67 No 4 R400U-188 Spray coat 98 60-67 No 5 R200U-188 Roll coat 16765 No 6 EF3-700C-188 Knife coat 176 90 Yes 7 R600U-090 Roll coat 9260-67 No 8 Mini-Standard Roll coat 65 36 No 9 Mini-Standard Roll coat 9055 No Com- EF3-700C-188 Knife coat 176 90 No parative A

Comparative Example B

Comparative Example B was a 6 inch diameter (15 cm) abrasive finishingdisc available under the trade designation Abralon™ 2000 from MirkaAbrasives Incorporated, Twinsburg, Ohio.

Comparative Example C

Comparative Example C was a 6 inch diameter (15 cm) abrasive finishingdisc available under the trade designation BUFLEX™ PN 192-1501 fromEagle Abrasives Incorporated, Norcross, Ga.

Product Testing

Materials

AOEM clear coated black painted cold roll steel test panels obtainedfrom Advanced Coating Technologies Laboratories, Inc., Hillsdale, Mich.having dimensions of 18 inches by 24 inches (45.7 cm by 61 cm).

Fine Finish orbital sander available from Dynabrade, Inc. of Clarence,N.Y. under the trade designation Dynorbital™ Model No. 56964 equippedwith a 3M™ Hookit™ II 6 inch (15.2 cm) diameter backup pad.

Water spray bottle.

Stopwatch.

Profilometer available from Federal Products Corporation an EsterlineCompany of Providence, R.I. under the trade designation Pocket Surf™profilometer.

Panel Preparation

The painted panels deployed horizontally in their long dimension werefirst prepared by sanding their surfaces using the fine finish sanderand 3M™ Hookit™ II Finishing Film Discs, grade P1500, available from 3MCompany under the trade designation 3M™ Hookit™ II Finishing Film Discs.The orbital sander was operated at a line pressure of 50 psi (3.52kg/cm²) using moderate but consistent downward pressure. Each sweep ofthe sander was overlapped by 50% with the pad half off the panel on thefirst and last sweep. Sanding was started in the upper left hand cornerof the test panel and the sanding pad was moved back and forth acrossthe panel, moving from top to bottom, ending at the lower right cornerafter a total of seven sweeps. The sander was then moved in a reversepattern, back up the panel in seven sweeps, ending at the startingpoint. The same sanding disc was then moved in a vertical path from theupper left corner, sweeping vertically, moving from left to rightending, after nine sweeps, at the lower right hand panel corner. Thesander was then moved in a reverse pattern, back across the panel innine sweeps, ending at the starting point. A new P1500 abrasive disc wasthen used, starting at the lower right panel corner and finishing at theupper left corner after seven horizontal sweeps. The sander was movedfrom the upper left corner horizontally moving back down the panel,ending at the lower right corner after seven sweeps. Sanding thenproceeded from the lower right corner vertically across the panel,ending at the upper left corner after nine sweeps. Finally, sanding wascontinued vertically, starting at the upper left corner, moving fromleft to right, ending at the lower right in nine sweeps.

Initial Finish of Prepared Panel

Using the profilometer, the Rz in the vertical center of each verticalone-third of the panel was read. Five readings were taken in eachone-third of a panel at 3 inches (7.6 cm) above and below the verticalcenter and at the vertical center. The average of these readings was theinitial Rz for the prepared test panel.

Abrasive Product Evaluation

The test abrasive products were converted into a six inch (15.2 cm)diameter pads to which was applied the 3M Hookit™ II attachment partthat was engageable to its mating part on the support pad of the finefinish sander. The test pad was mounted on the support pad of the sanderand was used to finish the prepared panel. The panel was considered tohave 3 equal sized vertical portions. Water was sprayed over the panelin a sufficient amount to prevent chattering or sticking of the productto the panel. One test disc was used on each panel. Sanding was in avertical direction in each one-third panel part under an appliedconstant hand pressure. The left most one-third portion was sanded for10 seconds, the middle portion for 20 seconds and the right portion for30 seconds. Three panels were sanded for each test product. The R_(z) ofeach sanded portion was measured in each vertical portion at 5 points,at the vertical center, 1.5 inch (3.8 cm) above and below the verticalcenter and 3.0 inches (7.6 cm) above and below the vertical center. Theaverage R_(z) for each sanding time is then reported with the initialR_(z). The results are shown in Table 4. TABLE 4 R_(z) Following VariousSanding Times Example 0 sec 10 sec 20 sec 30 sec Stick to panel? 1 37.915.7 13.6 14.4 No 2 37.3 16.8 12.3 13.6 No 3 37.6 16.3 14.9 14.9 No 437.2 16.8 13.3 15.5 No 5 37.7 19.5 16.8 15.7 No 6 37.5 16.5 13.1 13.6 No7 34.3 10.9 8.8 8.8 No 8 33.5 13.3 10.9 10.9 No 9 33.6 12.0 10.1 11.2 NoComparative A 37.8 18.9 12.8 14.4 Yes Comparative B 37.8 42.5 34.0 31.2No Comparative C 37.5 21.6 17.3 14.1 Yes

It can be seen that the abrasive products of the present inventionprovide a lower R_(z) faster than comparatives B and C. The products ofthe invention are also easier to handle during use.

The present invention has now been described with reference to severalembodiments thereof. It will be apparent to those skilled in the artthat many changes can be made in the embodiments described withoutdeparting from the scope of the invention. Thus, the scope of thepresent invention should not be limited to the structures describedherein, but rather by the structures described by the language of theclaims, and the equivalents of those structures.

1.-17. (Canceled)
 18. A flexible abrasive article comprising: a. foambacking having a minimum thickness of at least 2 mm, a first majorsurface and an opposite second major surface; and b. a shaped abrasivecoating having recessed portions and raised portions comprised ofabrasive particles in a binder over said first major surface of the foambacking.
 19. The flexible abrasive article of claim 18 wherein said foambacking is an open cell foam backing.
 20. A method of making an abrasivearticle, said method comprising the following steps: a. providing a foambacking having a minimum thickness of at least 2 mm, a first majorsurface, and an opposite second major surface; b. adhering to the secondmajor surface one part of a two part attachment sheet material toprovide dimensional stability to foam backing; c. applying a shapedcoating composition comprising a curable binder and abrasive particlesover said first major surface of foam backing, said coating compositionbeing curable to provide a shaped abrasive coating; and d. curing thecurable binder.
 21. The flexible abrasive product of claim 18 whereinthe foam backing has a contoured surface including a regular array ofprojecting portions and recessed portions.